Field of the Invention
The present invention relates to wireless communication, and more particularly, to a method and an apparatus for transmitting a data unit in a wireless local area network (WLAN).
Related Art
Data is delivered through data units that are referred to as a physical layer protocol data unit (PPDU) of the IEEE 802.11. The PPDU may broadly include a physical (PHY) preamble, a PHY header, and a Physical layer service data unit (PSDU). The PHY preamble is used for delivery, such as signal detection, time and frequency synchronization, channel estimation, and so on, and may include a training symbol. The PHY header may transmit a TXVECTOR. As a medium access control) protocol data unit (MAC PDU), the PSDU may correspond to information that is sent down from the MAC layer. As a data unit that is generated in the MAC layer, the MPDU may include a MAC header and a MAC service data unit MSDU.
The goal of the next generation WLAN system is 1) to enhance a 802.11 physical (PHY) layer and a MAC(medium access control) layer in bands of 2.4 GHz and 5 GHz, etc., 2) to enhance spectrum efficiency and area throughput, and 3) to enhance performance in actual indoor environments and outdoor environments, such as an environment where an interference source exists, a dense heterogeneous network environment, an environment where user load exists, and so on. The scenario that is mostly considered in the next generation WLAN system corresponds to a dense environment where a large number of access points (APs) and stations (STAs) exist. In the next generation WLAN system, discussion is made on the enhancement of spectrum efficiency and area throughput under such environments. Most particularly, in addition to the indoor environments, the next generation WLAN system is interested in actually enhancing the performance in outdoor environments, which was not significantly considered in the conventional WLAN system.
Furthermore, in the next generation WLAN system, extensive discussion is expected to be carried out on the enhancement of system performance in an overlapping basic service set (OBSS) environment, the enhancement of performance in outdoor environments, cellular off-loading, and so on, rather than the enhancement of a single link performance in a single basic service set (BSS).